Fuse construction



June 26, 1962 A. SOMMERS 3,041,428

FUSE CONSTRUCTION Filed Jan. 5, 1961 ALEX/5 My? Afforneys V EN TOR.

United States Patent Ofiice 3,041,428 Patented June 26, 1962 3,041,428 FUSE CONSTRUCTION Alexis Summers, Warren, Pa., assignor to El-Tronics, Inc., Warren, Pa., a corporation of Pennsylvania Filed Jan. 5, 1961, Ser. No. 80,776 3 Claims. (Cl. 200-131) This invention relates to a new and improved circuitprotecting fuse. More particularly, the invention relates to a new fuse structure which has improved durability and which may be assembled simply and conveniently.

One of the disadvantages of fuse constructions hereto fore proposed has been the difliculties in handling partially assembled fuse components during the manufacturing operations. Customarily, with cartridge-type fuses having blade contacts, a blade is secured to each end of a fusible link and this sub-assembly is placed in a cylindrical open-ended fuse cartridge after which caps are positioned over the ends of the cartridge.

Since the fusible link generally has portions of relatively thin cross-section, there is a tendency for the link to be deformed if it is not firmly held within the cartridge. When the caps are secured to the ends of the cartridge, it is important that they be carefully positioned to avoid twisting the blade ends relative to each other and to avoid applying excessive forces to the end portions of the blades so that there will be substantially no distortion or bending of the fusible link. The fusible link also may be deformed when the fuse is being filled with an arcquenching powder since during this operation the fuse is customarily subjected to a strong vibratory force to compact the powder in the cartridge.

The fuse construction of the present invention provides means for minimizing possible damage or deformation of the fusible link. Moreover, the fuse construction also provides improved means for aligning and maintaining proper alignment of the assembled components of the fuse during subsequent manufacturing operations and the later handling of the completed fuse. An additional advantage of the fuse structure of the invention is the improved resistance to shock such as might be caused by dropping or jarring.

Other advantages and features of the fuse structure of the present invention will be apparent from the following detailed description and drawing in which:

FIGURE 1 is an exploded view of a fuse of the invention without the end closures.

FIGURE 2 is a view partly in section of the fuse shown in FIGURE 1 with the various parts in proper position and with an end closure in position for assembly.

FIGURE 3 is an enlarged sectional view taken along line 3-3 of FIGURE 2.

FIGURE 4 is an end View of the fuse shown in FIG- URE 2 with the end enclosure in position.

FIGURE 5 is a fragmentary view showing an end portion of another fuse.

As shown in the drawing, a cartridge fuse of the invention comprises a fusible link 11 to the ends of which are secured conductive blades 12 and 13. Disposed along the fusible link 11 are supports 15 and '16 made of an insulating material. These insulating supports function to retain any arc-quenching material which may fill the space between the fusible link and a shell or housing 17 made of an insulating material such as fiber.

Conductive blades 12 and 13 have positioned along their length, abutments 18 and 19 spaced apart a predetermined distance which is slightly greater than the length of housing 17. Such abutments may be heavy metallic discs or portions of discs which are mechanically pressed into tight engagement with the blades. Preferably, the blades are provided with shoulders against 2 which the abutments bear to prevent displacement of the abutments outwardly from the end portions of the fusible link.

As shown in FIGURE 2, the fusible link-blade subassembly is positioned within tubular housing 17 with a conductive blade and an abutment extending from each end of the housing. To maintain the link-blade subassembly properly aligned with respect to the housing, biasing elements or spacers such as spring washers 21 and 22 shown in the drawing are inserted between the ends of the housing 17 and the abutments 18 and 19, respectively.

Spring washer 21 has struck-up center portions 24 which bear against abutment 18 while the peripheral portion of washer 21 bears against the annular end of housing 17. In the same way, washer 22 positioned at the opposite end of housing 17 has struckup center portions 25 which bear against abutment 19 while the peripheral portion of washer 22 bears against the opposite annular end of the housing.

By the insertion of the washers 21 and 22 at the ends of the housing 17, the fusible link-blade subassembly is maintained under tension thereby preventing movement of the subassembly and maintaining proper alignment of the subassembly Within the housing. Also, the subassembly is cushioned against shocks which might damage the fusible link if the subassembly were dropped or handled roughly.

Assembly of the fuse is completed by sliding an outer washer 27 over the end of the contact blade 13 extending from the housing 17 and positioning the washer against abutment 19. Thereafter, a retaining cap 28 having an opening in the end thereof 29 of a size slightly larger than the larger dimension of the blade cross-section is passed over the end of the blade 13 and suitably secured to the end of housing 17, which is shown in the drawings as a threaded engagement. As the cap 28 is tightened on the threaded end portion of housing 17, the cap will move over the washer 28 and force the washer against abutment 19.

In the same way, a second outer washer and a second cap similar to washer 27 and cap 28 are inserted over blade 12 and secured to the opposite end of housing 17.

As shown in FIGURE 5, the ends of housing 17 also may be closed by using caps such as cap 31 having a slot 32 therein through which the contact blade 33 extends. In this case, the cap 31 may be suitably secured to the housing, for example, with rivets 34. The employment of such a combination may be preferred in some cases since it eliminates the need for the outer Washers and the threaded portions on the housing and caps.

From the above description, it will be apparent that the fuse structure of the present invention has improved resistance to shock which might otherwise damage the fusible link or other components of the fuse. As a result, the fuse structure of the invention minimizes the fuse damage which might result from rough handling during manufacturing, packaging, shipping or use. An additional advantage of the fuse structure of the invention is that the construction compensates for slight variations in the size of the housing or spacing of the abutments without requiring special assembly procedures. Further, the link is maintained under tension even if changes occur in the relative lengths of the housing or fuse link due to heat or cold or to moisture conditions. Moreover, the fuse structure of the invention may be simply and conveniently assembled without bending or otherwise distorting the fusible link during assembly and capping operations.

It is apparent from the above description that various modifications may be made in the particular fuse structure described. For example, the size and configuration of the various fuse components may be changed to provide for particular requirements. Also, the conductive blades 12 and 13 may be secured to fusible link 11 in a manner which will permit the fuse to be renewed by substituting a new fusible link 11 for a ruptured fuse link. This may be accomplished, for example, by bolting or otherwise removably attaching the fusible link member 11 to the blades.

Since, as pointed out above, various modifications can be made within the scope of the invention, the invention is not intended to be limited to the particular fuse structure described in detail herein, except as may be required by the appended claims.

What is claimed is:

l. A circuit-protecting fuse comprising an insulating housing, a fusible link member positioned within said housing and extending from the ends thereof, abutments rigidly disposed on the portions of said link member extending from the ends of said housing, said abutments being spaced outwardly from the ends of said housing, a pair of biasing spacers positioned between the ends of said housing and the abutments of said link member, each of said spacers having a peripheral pontion which bears against an end of said housing and a central portion which bears against the abutment on said link member thereby maintaining said link member under tension and substantially preventing movement of.said link member relative to said housing, and cap members overlying the ends of said housing and secured thereto.

2. A circui t-protecting fuse comprising an insulating housing, a fusible link member axially aligned within said housing, said link member having conductive blades secured to the ends thereof which extend from the ends of said housing, abutments rn'gidly disposed on the portions of said blades extending from the ends of said hous' ing, said abutments being spaced outwardly from the ends of said housing, a pair of biasing spacers positioned between the ends of said housing and the abutments of said blades, each of said spacers having a peripheral portion which bears against an end of said housing and a central portion which bears against the abutment on said blade thereby maintaining said link member under tension and substantially preventing movement of said link member relative to said housing, and cap members overlying the ends of said housing and secured thereto.

3. A circuit-protecting fuse comprising an insulating housing, a fusible link member axially aligned within said housing, said link member having conductive blades secured to the ends thereof which extend from the ends of said housing, said blades having shoulder portions on the outwardly extending. portions thereof, abutments rigidly disposed on said blades and bearing against the shoulder portions thereof, a pair of biasing spacers positioned between the ends of said housing and the abutments of said blades, each of said spacers having a peripheral portion which bears against an annular end of said housing and a central portion which bears against the abutment on said blade thereby maintaining said link member under tension and substanially preventing movement of said link member relative to said housing, and cap members overlying the ends of said housing and secured thereto.

References Cited in the tile of this patent UNITED STATES PATENTS 780,544 Varney Jan. 22 1905 1,280,478 Horton c. Oct. 1, 1918 2,292,058 Craig Aug. 4, 1942 2,471, 177 Von Hoorn May 24, 1949 FOREIGN PATENTS 620,641 Germany Oct. 24, 1935 

